JPS58206603A - Acrylic emulsion - Google Patents

Abstract

PURPOSE:The titled emulsion that is obtained by emulsion polymerization of an alpha,beta-ethylenically unsaturated monomer in the presence of a water-soluble polymer emulsifier such as polyacrylic acid, thus giving coating films, which are chemically stable to metal ions and have high resistance to folding and scratching. CONSTITUTION:The objective emulsion is obtained by emulsion polymerization of an alpha,beta-ethylenically unsaturated monomer in an aqueous medium in the presence of 5 or more pts.wt. per 1,000pts.wt. of the monomer on the solid basis, of polyacrylic acid and/or a copolymer containing more than 50wt% of acrylic acid and at least one selected from methacrylic acid, acrylic or methacrylic acid amides and hydrophilic monomers of the formula (A is H, methyl; R is 2-4C alkylene; X is functional group containing at least one of O, P, S) such as 2- hydroxyethyl methacrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an acrylic emulsion, and more specifically, by emulsion polymerizing α,β-ethylenically unsaturated monomers using a specific water-soluble polymer as an emulsifier, metal ions and inorganic Acrylic emulsions that have excellent chemical stability against ions and exhibit excellent corrosion resistance, moisture resistance, and paint adhesion as well as excellent bending and scratch resistance when applied to metal materials as a paint base. It is. j As a base treatment method for metal painting, a non-reactive film-forming method in which a treatment solution containing a synthetic emulsion and a water-soluble chromium compound is applied to the metal surface has been proposed to simplify the management of the treatment process and reduce the problem of wastewater pollution. Recently, it has been attracting a lot of attention due to its avoidance. Many proposals regarding such technology have already been made (Japanese Patent Application Laid-open No. 57931-1983,
No. 31026, No. 49-40865, No. 50-188
(Refer to No. 9), both emulsions are manufactured in the presence of relatively large amounts of nonionic or anionic surfactants, so when painting after forming a base film, the adhesion, corrosion resistance, and moisture resistance of the paint film may be affected. A severe deterioration in sexuality was unavoidable.

Further, when chromate is added to the emulsion, in order to prevent the formation of deterioration products in the resin, for example, in Japanese Patent Publication No. 49-31026, the treatment solution is cooled to below 20 DEG C., and handling is not necessarily easy. Under such circumstances, the applicant has previously proposed that polyacrylic acid and/or acrylic acid and methacrylic acid, acrylamides, methacrylamides and the general formula % (wherein A is a hydrogen atom or methyl group, R is C2-C4
a substituted or unsubstituted alkylene group, and X is a functional group having at least one of an oxygen atom, a phosphorus atom, and a sulfur atom). Using 20 to 50 parts by weight of the solid content per 100 parts of α,β-monoethylenically unsaturated monomer, emulsion polymerization of the α,β-monoethylenically unsaturated intermediate will result in an extremely stable emulsion. It has excellent corrosion resistance, does not produce resin deterioration products even when chromate is added, and has excellent corrosion resistance.
He discovered that it was possible to provide a base film with excellent moisture resistance and paint film adhesion, and filed a patent application for a method for producing such a water-based polymer and a method for surface treatment of metal using the emulsion (Japanese Patent Application Laid-Open No. 1983-1993). 96683 No. 2 53-4086
No.: No. 52-133837, No. 53-49029). The present invention is a further development of these inventions. Furthermore, regarding the polymerization of α,β-ethylenically unsaturated monomers in an aqueous medium using specific polyacrylic acid or its ammonium salt and without using ordinary emulsifiers, Japanese Patent Application Laid-Open No. 74934/1989 discloses There is also a description.

However, as mentioned above, the emulsions obtained by emulsion polymerization of α,β-ethylenically unsaturated monomers using these specific types and ship polymers have excellent chemical stability against metal ions and inorganic ions. Since the surface treatment liquid based on this emulsion does not contain surfactants, it provides a base film with excellent corrosion resistance, moisture resistance, and coating adhesion. It was also found that the performance of the treated films differed in terms of workability, that is, folding resistance and scratch resistance. Therefore, the object of the present invention is to provide a synthetic resin emulsion for use as a coating type treatment agent that is easy to manage and does not cause problems such as wastewater treatment, which is chemically stable against metal ions and has excellent corrosion resistance, moisture resistance, and coating adhesion. It is an object of the present invention to provide a synthetic resin emulsion which can not only provide an excellent film, but also a film which is particularly excellent in inorganic salt stability, and has excellent foldability and scratch resistance.

As a result of intensive research to achieve this objective, the present inventors found that the glass transition temperature of emulsion resin [(T-a)
It was unexpectedly found that these performances are closely related. The glass transition temperature is recognized as a turning point at which the physical properties and behavior of polymers such as specific volume and rigidity change significantly, but it is also an important factor that affects the bending resistance and scratch resistance of resins. This was completely unexpected, and the industrial significance of the present invention, which was completed based on this new knowledge, is extremely significant.

The gist of the present invention is, as clearly defined in the claims, as follows:
5 or more parts of polyacrylic acid and/or acrylic acid and methacrylic acid, acrylamides, methacrylamides and the general formula % formula % (wherein A is a hydrogen atom) per 100 parts by weight of the unsaturated 111m body. or methyl group, R is C2-C4
a substituted or unsubstituted alkylene group, and X represents a functional group having at least one of an oxygen atom, a phosphorus atom, and a sulfur atom) A copolymer with at least one selected from the group consisting of hydrophilic monomers shown in C. It is produced by emulsion polymerization in the presence of an emulsifier, and the glass transition temperature of the resulting polymer is 1.
Acrylic emulsion characterized by a temperature within the range of 5°C to 110°C.

The water-soluble polymers used as emulsifiers in the present invention are polyacrylic acids and copolymers of acrylic acid and other hydrophilic monomers.

Other hydrophilic polymers in the above copolymer include:
Methacrylic acid, acrylamides (e.g. acrylamide, N-methylolacrylamide), methacrylamides (e.g. methacrylamide, N-methylolacrylamide) and hydrophilic polymers represented by the -1-open general formula (e.g. Acrylic! 12-hydroxyethyl, human 1koxyprobyl acrylate, 2-hydroxy U'' methacrylate, human D4-dipropyl methacrylate, 3-hydroxybutyl acrylate, acrylic acid 2゜2
-bis(human[]oxymethyl)ethyl, methacrylic acid 2
, 3-dihydroxypropyl, 3-hydroxybutyl methacrylate, etc., when X is a functional group having a phosphorus atom, mono(2-hydro4diethyl methacrylate) acidophosph 1-1-CH30 3-Chloro-2-human []xypropyl methacrylate) acid phosphate CH30 111 CH2=CCOCH2CHOP 0HII
When x is a functional group that also has a sulfur atom, such as l l OCHz CI OH, sulfonylethyl methacrylate, etc.) are used, and at least one selected from these groups is subjected to copolymerization. Bye.

The proportion of acrylic acid and other hydrophilic polymers in this copolymer is not particularly limited, but the proportion of acrylic acid in the total monomers is usually 50% by weight or more, preferably 60% by weight or more. It may be selected appropriately so that If the acrylic acid content is less than 50% by weight, the function of the copolymer as an emulsifier will be adversely affected, the system stability of the aqueous polymer obtained by emulsion polymerization will decrease, and the aqueous polymer may not be used in the coating composition. When used as a coating, the moisture resistance and corrosion resistance of the coating, and especially when used as a metal coating composition, the adhesion to the metal substrate tends to decrease.

The production of such a water-soluble polymer may be carried out according to a conventional method (polymerization method in an aqueous solution, bulk polymerization method, polymerization method in an organic solvent, etc.). , acrylic acid alone or a mixture of a predetermined proportion of acrylic acid and at least one other hydrophilic additive, and a suitable water-soluble free radical catalyst (e.g. ammonium persulfate, potassium persulfate). and 2
Water (preferably deionized water) containing ゜2-azobis-(2-amidinopropane)-hydrochloride) is added from outside a separate dropping port into water (preferably deionized water) maintained at the reaction temperature. They may be added dropwise at the same time and, if necessary, aged at the same temperature. The reaction is carried out under stirring, the reaction temperature is usually 70 to 90°C, and the reaction time (dropping time plus aging time) is usually 3 to 5 hours.

Various water-soluble polymers in the form of solutions can be obtained as described above, and these polymers may be used alone or as a mixture of two or more as an emulsifier. Used is α, β-monoethylenically unsaturated monomer 10 to be subjected to emulsion polymerization.
The solid content is 5 parts by weight or more, preferably 5 parts by weight based on 0 parts by weight.
-100 parts by weight. Even if the amount used is less than 5 parts by weight, the emulsion polymerization described below can be carried out sufficiently, but the desired level of storage stability of the aqueous polymer cannot be obtained, and it cannot be practically used as a coating composition. It disappears. Furthermore, even if the amount exceeds 100 degrees, the storage stability and chemical stability of the aqueous polymer will not improve any further, and problems such as foaming of the aqueous polymer will arise.

Furthermore, the molecular weight of the water-soluble polymer influences the function of the polymer as an emulsifier, which in turn greatly influences the storage stability of the water-soluble polymer and the various performances of the coating when used as a coating composition. For example, if the molecular weight is too low, the emulsifying effect will increase and the storage stability of the aqueous polymer will improve, but the moisture resistance and corrosion resistance of the coating will decrease. Also,
If the molecular weight is too high, the emulsifying effect will be reduced, making it impossible to obtain a uniform and stable aqueous polymer. Therefore, from this point of view, the molecular weight of the water-soluble polymer is usually 5.000 to 300.0.
It is desirable to set it in the range of 00, preferably 10,000 to 1oo, ooo.

In the present invention, as the α, β-1 tyrene bamboo unsaturated ψ polymer to be subjected to emulsion polymerization, ordinary ones are used, such as acrylic@l esters (methyl acrylate, decyl acrylate, isopropyl acrylate, n -1 tyl, 2-ethyl acrylate ↓sil, decyl acrylate,
Isoocdyl acrylate, 2-X methylbutyl acrylate, octyl acrylate, methoxy J-methyl acrylate, I l-, r-sil acrylate, 3-1 toxyprobyl acrylate, etc.), methacrylic esters (methyl methacrylate, Ethyl methacrylate, isopropylene methacrylate, methacrylate@n-butyl, iso-ethyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, decyl octyl methacrylate, stearyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Glycidyl, 2-2F toxyethyl methacrylate,
One or more of the following are used: cetyl methacrylate, benzyl methacrylate, M3-methoxydipyl methacrylate, etc.), acrylonitrile, methacrylate, vinyl acetate, vinyl chloride, vinyl ketone, vinyltoluene, and styrene. In addition to these, a small amount of acrylamides, methacrylamides, which are constituent members of the above-mentioned water-soluble copolymer, and hydrophilic monomers represented by the above general formula may be added. In particular, when the aqueous polymer obtained by adding a monomer having an OH group such as 2-hydroxy]dityl methacrylate is used as a coating composition for metals, the C0OH group in the emulsifier is removed by baking and drying the coating. Because it adopts a cross-linked structure, it is observed that the adhesion to the metal substrate is significantly improved.

However, in the present invention, the above-mentioned α, β-ethylenically unsaturated monomers, or combinations thereof, and their quantitative proportions are such that the glass transition temperature of the produced polymer is 15°C to 11°C.
It needs to be selected so that it is within the range of 0°C. If the glass transition temperature of the resulting polymer is less than 15°C,
In particular, a film with sufficient bending resistance and scratch resistance cannot be obtained. Furthermore, a polymer having a glass transition temperature of 110 DEG C. or higher cannot be obtained from a commonly used α,β-ethylenically unsaturated monomer. Glass transition of the polymer is particularly preferable in terms of bending resistance and scratch resistance when blending a chromic acid-based or phosphoric acid-based chemical conversion treatment agent with the produced emulsicon and using it as a coating type treatment agent for the purpose of metal surface treatment. The temperature is 40°C to 110°C.

In the emulsion polymerization of the present invention, the above-mentioned water-soluble polymer is used as an emulsifier, and α,β-ethylenically unsaturated monomers having a glass transition temperature of 15°C to 110°C are selected from among the usual types mentioned above. The process may be carried out according to conventional conditions and techniques, except for selectively using those which give a polymer of .

For example, a selected α,β-ethylenically unsaturated monomer and a water-soluble catalyst (
For example, ammonium persulfate and sodium persulfate) and, if necessary, water (preferably deionized water) containing the remainder of the emulsifier are simultaneously dropped from outside separate dropping ports and, if necessary, aged at the same temperature. The polymerization is carried out under stirring, and the polymerization temperature is usually 50 to 90°C, and the polymerization time (dropping time + aging time) is usually 3 to 7 hours.

Through this emulsion polymerization, the solid content is 5 to 50% and the particle size is 0.
．． A uniform and stable emulsion of an aqueous polymer having a glass transition temperature of 15°C to 110°C can be obtained at 1 to 2μ. This acrylic emulsion eliminates the negative effects of surfactants in conventional methods when used as a coating composition, and not only has excellent storage stability (more than 3 months) but also contains various metals in the system. It has excellent chemical stability that does not impair system stability even when a large amount of ions or inorganic ions are mixed in. In addition, when a chromic acid-based or phosphoric acid-based chemical conversion treatment agent is added to the emulsion and used for metal surface treatment,
The remarkable feature of the present invention is that it not only provides a base film for painting with excellent corrosion resistance, weather resistance, and film density, but also provides a coating film with excellent processability, that is, bending resistance, and scratch resistance. This is also an important feature. In addition, when using a darkening aqueous polymer as a coating composition, epoxy resins (e.g., bisphenol-type commercial products manufactured by Shell Chemical Co., Ltd. under the trade name "1-bi") are usually used as curing agents.
8.28 J, the same [Epicote 1゜01'')...
It is also possible to mix it into the emulsion polymerization system and make it stably exist in IJ. For example, in the above emulsion polymerization, the epoxy resin C1 may be dissolved in an α,β-ethylenically unsaturated monomer and then added dropwise.

From the above, it can be seen that the acrylamides according to the present invention can be used in various coating compositions, and are particularly effective as coating compositions for metals.

The present invention will now be explained in detail with reference to Examples and Comparative Examples. In the example sentences, "part" and "%" mean "1 part by weight" and "1-weight%".

Example 1 A water-soluble polymer obtained by polymerizing 150 parts of deionized water and acrylic acid (25% aqueous solution,
Add 120 parts of molecule 1 (MW) 66000) and stir T;
Stomach thirst at 75-80℃. Next, a catalyst solution consisting of a monomer mixture consisting of 45 parts of methyl methacrylate, 27 parts of styrene, 9 parts of methacrylic 1f2-hydroxylethyl, and 9 parts of n-butyl methacrylate, 2 parts of ammonium persulfate, and 50 parts of deionized water was added. Drop simultaneously from outside of separate drip openings after 3 hours. After completion of the dropwise addition, aging is further carried out at 75 to 80° C. for about 2 hours to complete the polymerization reaction.

The resulting emulsion has a solid content of 29°8% and a pH of 1.6.
It is a uniform and stable emulsion with a particle size of 0.3μ and a core portion T(] of 89°C.

To the emulsion described in F, chromic anhydride was partially reduced with formalin (3+ chromium aqueous solution < 20% aqueous solution), and 1 was added so that the solid content ratio was 1:1, and left at room temperature for 3 months. There are only 0 muic acid and 1 full dione.
Although layers were formed and a small amount of precipitate was formed, the mixture immediately returned to its homogeneous state just by stirring, and it was observed that the symptoms were no different from the initial symptoms. In addition, after treating a galvanized steel sheet with the surface treatment agent prepared in this way, it exhibited very good performance in terms of surface finish, scratch resistance, and foldability.

Example 2 In a flask similar to Example 1, 150 parts of deionized water and a water-soluble copolymer (25% aqueous solution) obtained by copolymerizing acrylic acid and 2-hydroxylethyl methacrylate at a weight ratio of 9:1. , molecule-MW65000) 120
of the mixture and raise the temperature to 80-85°C while stirring. This is then treated with a monomer mixture consisting of 50 parts of methyl methacrylate, 30 parts of styrene, 10 parts of methacrylic 8!2-human C xylethyl and 10 parts of n-butyl methacrylate, 2 parts of ammonium persulfate and 50 parts of deionized water. and the catalyst solution were simultaneously dropped over a period of 3 hours from the outside of separate dropping ports. After completion of the dropwise addition, aging is further carried out at 80 to 85° C. for about 2 hours to complete the polymerization reaction. The resulting emulsion had a solid content of 30.1%, 1)+11.
6. It was a uniform and stable emulsion with a particle size of 0.2μ and T (189°C.) For the above emulsion, a chromium aqueous solution (20% aqueous solution) prepared by partially reducing chromic anhydride with formalin to form Cr3+ was solidified. When the mixture was added at a ratio of 1:1 and left at room temperature for 3 months, the chromic acid and emulsion were slightly separated into two layers and a small amount of precipitate was formed. It was observed that the properties were not different from those at the initial stage.

Also, galvanized steel sheets treated and painted with the metal surface treatment agent prepared by the above method have corrosion resistance, bending resistance,
It was a painted board with very good scratch resistance.

Example 3 Monomer mixture was 40 parts of methyl methacrylate and 2 parts of styrene.
Emulsion polymerization was carried out in the same manner as in Example 2, except that the following ingredients were used: 10 parts of 2-hydroxylethyl methacrylate, 20 parts of n-butyl acrylate, and 10 parts of acrylonitrile. The resulting aqueous polymer had a solid content of 30.3% and a pH of 1.6.
It was a uniform and stable emulsion with a particle size of 0.2μ and a Tq point of 52°C.

In addition, when a sample was prepared in the same manner as in Example 2, two layers were slightly separated and a small amount of precipitate was formed, but the homogeneous system immediately returned to its original state by stirring. It was found that there was no difference at all.

Furthermore, a galvanized steel plate treated and painted with the metal surface treatment agent prepared by the above method was a coated plate with excellent corrosion resistance, folding resistance, and scratch resistance.

Comparative Example 1 Monomer mixture was 75 parts of ethyl acrylate and 15 parts of styrene.
Emulsion polymerization was carried out in the same manner as in Example 1, except that the mixture was composed of 10 parts of xyl ethyl, 8 m12 of methacrylic acid, and 10 parts of xylethyl. The obtained aqueous polymer had a solid content of 30.1%, a pH of 1,
It was a uniform and stable emulsion with a particle size of 0.2μ and a T( ) point of -2°C.Also, when the above emulsion was prepared in the same manner as in Example 2, two layers were slightly separated and a small amount of precipitate was formed. However, just by stirring it, it immediately returned to its original homogeneous system and its properties were no different from their initial properties.
In the same coating test as in Example 2, it was inferior to Example 1.2.3 in terms of corrosion resistance, folding resistance, and scratch resistance.

Comparative Example 2 Into the same flask as in Example 1, 100 parts of deionized water and 7 parts of a nonionic surfactant (trade name: Emulgun 950J, manufactured by Kao Atlas Co., Ltd.) are placed, and the temperature is raised to 80 to 85°C while stirring. Then implement this.

A monomer mixture having the same composition as in Example 1 and a catalyst solution consisting of 2 parts of ammonium persulfate and 20 parts of deionized water are simultaneously added dropwise from separate ports over a period of 3 hours. After the dropwise addition, the temperature was increased to 80 to 85°C for about 1 hour to further complete the polymerization reaction.
Perform time ripening. The resulting aqueous polymer has a solid content of 46.
3%, pH 1°3, viscosity 310cps, grain 41!0.1
It is a homogeneous and stable emulsion containing no gum of ~0.2μ.

When an aqueous chromium solution was added to the above emulsion at a solid content ratio of 1:1 as in Example 1, the entire system instantaneously coagulated, and the clear liquid had the color of an aqueous chromium solution.

Continuation of page 1 0 shots clear person Ryuzo Mizuguchi 19-17 Ikeda Nakacho, Neyagawa City Japan Inside Paint Co., Ltd.

Claims (1)

[Scope of Claims] (1) α, β-edylenically unsaturated skewers are mixed with polyacrylic acid and 7 parts of polyacrylic acid in terms of solid content per 100 parts by weight of the unsaturated type in an aqueous medium. or acrylic acid and methacrylic acid, acrylamides, methacrylamides and the general formula % formula % (wherein A is a hydrogen atom or a methyl group, R is a C2 to C4
at least one selected from the group consisting of a substituted or unsubstituted alkylene group, and X represents a functional group having at least one of an oxygen atom, a phosphorus atom, and a sulfur atom. An acrylic emulsion produced by emulsion polymerization in the presence of various copolymer emulsifiers, and characterized in that the resulting polymer has a glass transition temperature of 15°C to 110°C. (2) Emulsifier α, β-ethylenically unsaturated monomer i 100
The emulsion according to claim 1, wherein the emulsion is used at a solid content of 5 to 100 parts by weight per suspended portion. (3) The molecular weight of the emulsifier is 10.000 to 100°000
An emulsion according to claim 1 or 2. (4) Acrylic acid content as emulsifier is 50% by weight or more1
An emulsion according to any one of claims 1 to 3 using a copolymer of (5) The emulsion according to claim 1, which uses polyacrylic acid as an emulsifier. (6) Claim 1 or 2 which uses a polymer of acrylic acid and acrylamide as an emulsifier
Emulsion as described in Section. (7) The emulsion according to claim 1 or 2, which uses a copolymer of acrylic acid and methacrylamide as an emulsifier. (8) The emulsion according to claim 1 or 2, wherein a copolymer of acrylic acid and methacrylic M2-hydroxyethyl is used as an emulsifier. (9) The emulsion according to claim 1 or 2, wherein a copolymer of acrylic acid and mono(2-hydroxymethacrylate) acid phosphate is used as an emulsifier. (10) The emulsion according to claim 1 or 2, wherein a copolymer of acrylic acid, 2-hydroxyethyl methacrylate, and mono(2-hydroxyethyl methacrylate) acid phosphate is used as an emulsifier. (11) Acrylic acid and methacrylic acid as emulsifiers]
An emulsion according to claim 1 or claim 2 in which a polymer is used. (12) The emulsion according to any one of claims 1 to 11, which undergoes emulsion polymerization in the presence of a poxy resin. (13) The emulsion according to any one of claims 1 to 12, wherein the polymer content is 5 to 50% by weight of solids. (14) The glass transition temperature of the produced polymer is 40°C to 110°C.
The emulsicon according to any one of claims 1 to 13, which has a temperature of .degree.